The long-term objective of the project continues to be the development of an effective behavioral weight control program for obese patients with type II diabetes. A second goal, added in the current submission, is to determine whether behavioral techniques can also be successfully applied in those at risk for type II diabetes, namely obese individuals with a family history of diabetes. The proposed project is designed to investigate the effects of a structured exercise program and a structured very low calorie diet, used singly or in combination, within the context of a long-term behavioral treatment program. Previous studies evaluating diet and exercise interventions have had small sample size, included only short periods of structured exercise (thus potentially underestimating the effectiveness of exercise) and focused entirely on calorie restriction (rather than also attempting to modify the fat content of the diet). The current study will improve the methodology and the treatment interventions and will determine which type of intervention is most effective in producing weight loss, improving glycemic control, and reducing coronary heart disease risk factors in those with diabetes and in those at risk for the disease. We propose to recruit 200 obese type II diabetic patients and 200 obese subjects who have a family history of diabetes. These subjects will be randomly assigned to Usual Care, or to Behavioral Weight Control Programs focusing on Diet Only, Exercise Only, or the Combination. All treatments win be conducted over a 2 year. period with intervention meetings held over this entire period. Weight, glucose and insulin responses to an oral glucose load, HbA1, lipids, blood pressure, fitness, and eating and exercise habits will be assessed at baseline, 1 year and 2 years. This study will provide important information on whether diet, exercise, or the combination is the most effective intervention for type 11 diabetic patients and those who are obese and have a family history of the disease. In addition, treating diabetic individuals and those at risk within the same study will allow us to determine whether these two groups differ in adherence to the programs and/or in their physiological responses to treatment, and whether the same intervention is most effective for both groups.